Can You Use Exterior Paint on Interior

Can You Use Exterior Paint on Interior?

Tell me if this sounds like you.

After deciding your house needs a fresh coat of paint, you found some forgotten tins of exterior paint in your shed and wondered if you could use it inside.

Well, if it does, you’re not alone. It’s a common question.

Don’t worry! I’m a professional painter and decorator here to cut through the masking tape to tell you if you can use exterior paint on interior surfaces. Also, I’ll tell you what paints should be used for interior surfaces.

Let’s get to it!

Can You Use Exterior Paint on Interior Walls? - My Expert Opinon

The simple answer is exterior paint and interior surfaces don’t mix (pun intended).

It is not recommended to use exterior paint on interior walls for many different reasons, including the toxic nature of exterior paint, the fact it’s harder to clean, and because the finish you’ll get will be poor.

Let’s look at each of those in more detail:

Exterior Paint Has Higher VOCs

Exterior paints typically contain much higher levels of VOCs than interior paint. 

WHAT THE HECK ARE VOCs, I hear you saying. 

Put simply, VOCs are the harmful chemicals found in paints. 

The best way to picture them is to imagine the gases released from a car’s exhaust. Just as a car releases gases as it drives, VOCs are released as you paint. 

VOCs are really bad for air quality. And, when exposed to them for long periods of time, it can lead to negative impacts on your health. 

These include:

  • Respiratory problems
  • Eye irritation
  • Nose irritation
  • Headaches
  • Nausea

When you use exterior paint on your interior walls, you breathe in these harmful paint fumes. So, you are at a greater risk of these side effects than you would if you used interior paint.

This becomes an even bigger problem when you are living with babies, pets, or someone aged over 65, who are even more vulnerable to the dangers of breathing in VOCs.

So, my advice? AVOID. AVOID. AVOID.

If You Used Exterior Paint Indoors You'll Get A Poor Finish

Exterior paint takes a lot longer to cure than interior paint. And when you use them inside, it will take even longer because there is a lack of ventilation compared to the outdoors.

As a result, exterior paints used indoors won’t cure properly, resulting in blisters, cracks, and peeling not long after you finish painting.

Exterior Paints Have Poor Adhesion To Interior Surfaces

Exterior paint typically contains adhesion promoters that help it to adhere to exterior surfaces. However, this is not suitable for interior surfaces because of the different textures and materials of the interior of a house.

As a result, when you paint your interior with exterior paint, it won’t adhere properly, and the finish will be terrible, to say the least.

Exterior Paint Is Harder To Clean

Exterior paints are designed to be more durable than interior paint. That’s because they need to withstand the harsh effects of the elements like rain.

This is made possible by the particular resins used to make exterior paint, making them more resistant to fading, cracking, and peeling.

However, it also means exterior paint is resistant to cleaning products you might usually use to clean your interior walls. Therefore, using exterior paint indoors will be much harder to clean.

So, if you want to save yourself from an intense cleaning session every time you find dirt on your walls, it’s best to lock that tin of exterior paint away and grab some interior paint from your local DIY store.

Not only that, if you resort to harsher chemicals, you might find that they ruin the paint finish or even remove the paint entirely.

Best Emulsion Paint Choice For Interior Walls

Emulsion paint is the best choice for your interior walls.

That’s because it’s quick drying and durable, making it perfect for your high-traffic rooms, like your hallways or living rooms.

Interior trim painted with exterior paint

Can You Use Exterior Paint For Interior Trim?

Much like your interior walls, exterior paint can’t be used for interior trim. That’s because the ingredients in the exterior paint make it a poor match for interior trim – we’ll look at this in more depth shortly.

So, when it comes to can you use exterior paint on interior trim, there’s no good argument for why you should.

Here’s why:

Not Suitable

You wouldn’t use exterior paint for interior trim because it won’t give you the smooth finish you want.

That’s because, unlike interior paints, exterior paint is not made with ingredients that give good flow and levelling.

What does that mean exactly?

Flow and levelling properties refer to the ability for paint to be evenly spread on a surface to give a smooth and level finish.

So, if you decide to use exterior paint on your trim, you will probably be disappointed when you see brushmarks and imperfections on the surface.

Also, exterior paint typically isn’t as flat as interior paint. So, when you use exterior paint on interior trim, it won’t be able to withstand wear and tear and frequent cleaning like interior paint would.

Exterior Paint Can Be More Expensive

Take a trip down to your local DIY store, and you’ll find that exterior paints are more expensive than interior paints.

Why? Exterior paints, like masonry paint contain added ingredients that make them more durable and moisture-resistant. So, you will pay more money to paint your interior trim than you would using exterior paint.

And as I mentioned earlier, if you use exterior paint on interior trim, you will be left with a low-quality finish.

So, that means you’ll be paying more for using exterior paint in terms of both cost and the actual quality of the finish. A lose-lose situation.

As a result, the question goes from ‘Can you use exterior paint for interior trim?’ to ‘Why would you want to?’.

Best Paint Choice For Interior Trim

The best paint choice for your interior trim is semi-gloss paint.

That’s because semi-gloss paint has a small amount of sheen, which makes it great for high-traffic areas. But they are also easy to clean and durable.

Bathroom painted with interior bathroom paint

Can You Use Exterior Paint For Your Bathroom Walls?

If you know anything about exterior paint, you’ll know it can withstand harsh weather conditions.

With that in mind, you might wonder whether it’s a good idea to use it to paint your bathroom to give it an extra layer of protection from occasional splashes.

However, just because it can stand up against the harsh rain of a British summer, it doesn’t mean you should be using it to paint your bathroom walls.

Here’s why:

Water Resistance

Exterior paints can withstand moisture and harsh weather.

However, they don’t provide the same level of moisture resistance as paints specifically made for bathrooms.

And since bathrooms are high-moisture areas, exterior paints won’t provide the kind of moisture protection you need from your bathroom paint. Over time, this will lead to peeling, blistering, and mould or mildew growth.

On the other hand, interior paints contain additives like mildewcides and moisture-resistant properties to prevent these issues.

Low Quality Coatings

Exterior paint does not have the same qualities as interior paint. 

As a result, if you used exterior paint for your bathroom walls, you would find that the finish is far from what you would expect from a good paint finish. 

That’s because exterior paint gives a different sheen and texture when applied compared to interior paint. Therefore, you’ll find that there will be several issues with the quality of the finish, including:

  • Imperfections in the walls will be more obvious
  • The texture would be more coarse than if you used interior paint
  • Over time the paint colour would look inconsistent

Best Interior Emulsion Paint Choice For Your Bathroom

The best paint for your bathroom is a water-based emulsion paint with a moisture-resistant additive.

Painting your bathroom with this type of paint will ensure your walls are easy to clean, durable, and resistant to moisture. My personal favourite is Dulux Bathroom + Emulsion Paint.

Houses painted in different colours of Dulux Weathershield paint

Can You Use Weathershield Paint Indoors

Dulux Weathershield paints are paints specifically designed for use on exterior surfaces.

So, naturally, if you decide to use these paints indoors, you’re in trouble.

The best way for me to explain this is with a short story.

A few years ago, a customer in Brixton contacted me to paint their living room. Over the phone, they told me that they had a giant web of cracks going across the walls of the living room.

When I visited the home to inspect the work, the owner told me they used Weathershield paints to paint the room. After hearing that, I immediately knew what was wrong.

I explained to them that Weathershield paints are formulated to withstand the harsh conditions of the outdoors. Because of this, it tends to be more rigid and less flexible than interior paint. As a result, when you use it indoors, you’ll usually have issues like cracking.

We had to re-line and repaint the living room to resolve the damage. A much more expensive job than it needed to be.

The moral of the story is that you should not use Dulux Weathershield paint inside your house.

What do you do instead?

Well, if you really love Dulux paints, they have an excellent range of paints that you can use indoors.

Can I Mix Exterior and Interior Paint For Painting My House?

Mixing exterior and interior paint sounds like a bad science experiment. It’s without a doubt a recipe for a colourful disaster.

In all seriousness, mixing these paints would result in a paint that wouldn’t work well on interior or exterior surfaces.

That’s because when you mix interior and exterior paint, the chemical reaction would result in a paint that wouldn’t be suitable for either of these surfaces.

For example, due to the exterior paints stronger odours and VOCs, it wouldn’t be suitable for interior surfaces (as we mentioned earlier).

Similarly, interior paint is not formulated to be able to expand and contract with weather changes like exterior paint can. So, when you use a mix of these paints, you will run into issues like paint not adhering correctly and easily cracking and fading over time.

Get Help From A Professional Painter and Decorator

If you are unsure what paint to use, you can get help from a professional painter and decorator.

A professional painter will tell you exactly what paint would be best for your interior. Also, a decorator will ensure you avoid common mistakes like painting your interior with exterior paint, which could save a lot of money and hassle further down the line.

Our team of painters and decorators are based in Brixton. So, if you need a quote, feel free to contact us.